The invention relates to a method for producing amino acid chelate compounds. Furthermore, it relates to amino acid chelate compounds. Finally, it relates to the use of amino acid chelate compounds.
When metal compounds with amino acids undergo a reaction, so-called chelates are created. Chelate compounds exist among other things for the metals copper, zinc, manganese, iron, calcium, magnesium, cobalt, vanadium, selenium and nickel and for the amino acids glycine, lysine and methionine.
Amino acid chelate compounds are used among other places in animal food and fertilizer for supplying trace elements. Glycine chelates have been increasingly used in animal nutrition in recent years. In many tests on animals, improved performance and improved intestinal absorption with respect to trace elements made of inorganic compounds were observed. The efficiency of trace elements in food can be improved and the excretion rate can be reduced. The risk of a physiological undersupply and performance depression is reduced. Moreover, information on potential advantages of organically bound trace elements was published, e.g. improved zootechnical and reproductive performance, higher outer and inner egg quality, higher incorporation in bodily organs or tissues.
The following glycine chelates are legally permitted in food products and are currently available on the market (the E numbers according to the EU food additive regulation are specified in parentheses):                Glycine iron chelate hydrate (E1), short: iron glycinate        Glycine copper chelate hydrate (E4), short: copper glycinate        Glycine manganese chelate hydrate (E5), short: manganese glycinate        Glycine zinc chelate hydrate (E6), short: zinc glycinate        
The glycinates currently available on the market differ considerably in particular with respect to the trace element content, glycine content, solubility in water, colour and structure, pH value and quantity and type of inorganic anions (sulfates and chlorides). All so-called copper glycinates that have been on the market up until now are either displaced with anions and/or diluted with fillers and/or contain a glycine content that is too low for real duplicate complexing. The enormous differences are attributed to the respectively used production methods, the raw materials used and the selected reaction ratios between trace element and glycine.
The production of glycine chelates is extremely complex. It generally starts from solutions of the corresponding trace element compounds with glycine, which are brought to react at increased temperatures. Evaporation, crystallization, drying and milling follow.
The state of the art is described for example in U.S. Pat. Nos. 4,315,927A, 4,814,177A, 830,716A, 4,599,152A and 5,516,925A.
The patent application CN 2009/10030766.3 describes the production of zinc glycinate. Then, in the first step, 5 to 15% glycine is stirred with 5-10% nano ZnO with water at 50°-80° C. for 3 to 24 hours and then held at rest for 6 to 10 hours. In the second step, it is centrifuged at 3,000 to 8,000 min−1 and the centrifugate is dried in an oven at 80°-120° C. The third step comprises the crushing and the classification when greater than 80-120 mesh. In the application CN 2009/10030767.8, the same production method is described for calcium glycinate except for the omission of the centrifuging.
EP 1 529 775 B1 relates to a method for the production of chelates of metals with organic acids, which mainly work in an anhydrous medium. Metal oxides, hydroxides or salts are used. The organic acid ligand such as glycine, lysine, glutamic acid among other things and the respective metal compounds such as hydroxides like copper hydroxide, zinc hydroxide, iron hydroxide, manganese hydroxide etc. are immersed in anhydrous liquids like methanol, ethanol, i-propanol, hexane, petroleum ether etc. and mixed together at room temperature or at an increased temperature. Since water is also a reaction product, it must be removed with the help of a water separation device (e.g. Dean-Stark water separator). The removal of the respective metal chelate from the organic liquid takes place through filtration. After drying, the respective metal chelate represents a very fine powder as the finished product.
It can be seen in the exemplary embodiment in EP 1 529 775 B1 that the described production method requires a pretreatment of the used metal compounds. Thus, for example, the production of copper hydroxide starts with CuSO4.5H2O, which is stabilized with KOH at pH 10-11 for the precipitation of Cu(OH)2. This is followed by a double centrifugation, which is accompanied by washing processes in ethanol. For the production of copper glycinate, Cu(OH)2 is then mixed with glycine and this mixture is boiled in ethanol for 5 hours. The copper glycinate created under these conditions is filtered out and dried to powder.
The patent applications CN 92107282.1 and CN 2007/130121.0 describe the conversion of mixtures of copper acetate and glycine in a one-step, solid-state reaction in a ball mill. For this, a mixture of copper acetate and glycine is combined with water and sodium carbonate and subjected to wet grinding in a ball mill. After several hours of grinding, the suspension is dried, washed with ethanol, centrifuged and dried again.
DE 10 2004 039 486 A1 describes a dry process for producing organic trace element compounds. Any dry mixture of a metal oxide and a solid organic acid is exposed to mechanical stress through blows and pressure from a fine crushing machine such that the released enthalpy amount triggers a solid-state reaction into a metal salt-like compound.
The focus of this unexamined laid-open patent application is the production of zinc bismethionate made of mixtures of ZnO and methionine, which are milled together in the mixture. This is proven with a total of seven examples. The other three examples have mixtures of CuO and asparaginic acid (one of a total of 21 amino acids), mixtures of MnO and malic acid (carboxylic acid ester) as well as mixtures of Cr(OH)3 and nicotinic acid (alkaloids bound in a salt-like manner to plant acids) as the object.
The testing of the method has shown that operating errors can occur through caking of ground material on the mill walls. These cakings can cause the complete cementing of the grinding chamber, which can only be remedied again with the help of air hammers and eliminates an industrial use. Moreover, the product qualities are not reproducible.